Installing and initialising Jenkins JNLP slaves using runit

Run all jobs on slaves

A possible configuration for Jenkins is to run all jobs through JNLP slaves. These can be housed upon the same machine as the master or different machines. The benefit is that the slaves can be run as different users and so cannot overwrite configuration files.

Creating a jnlp slave

mkdir /srv/jenkins-slaves
adduser  --home /srv/jenkins-slaves/jslave jslave

Download http://localhost:21337/jnlpJars/slave.jar to /srv/jenkins-slaves Then as shown on the slave start page:

cd /srv/jenkins-slaves/jslave

java -jar slave.jar -jnlpUrl http://localhost:21337/computer/jnlp/slave-agent.jnlp \
   -secret 96742108603d1c4f19a7fe52133f7410d75a7287f9686d9e97276e3c1eae10d7

This can then be run under runit.

Add the following to /etc/sv/jslave/run

#!/bin/sh
set -e
exec 2>&1
export LANG=en_GB.UTF8
export LANGUAGE=en_GB:en
export LC_ALL=en_GB.UTF8
export HOME=/srv/jenkins-slaves/jslave

cd /srv/jenkins-slaves/jslave
# Secret and url copied from http://localhost:8081/computer/Runner/
chpst -u jslave \
 java -jar slave.jar -jnlpUrl http://localhost:8081/computer/Runner/slave-agent.jnlp \
  -secret 96742108603d1c4f19a7fe52133f7410d75a7287f9686d9e97276e3c1eae10d7

Add the following to /etc/sv/jslave/log/run

#!/bin/bash
set -e
exec svlogd /var/log/jslave

Then add a symlink into /etc/services and start the service:

ln -s /etc/sv/jslave /etc/service/
/usr/bin/sv start /etc/service/jslave

Now jobs can be configured through the Jenkins interface to run only on the slave runner.

You can extend this to many different slaves, each running a different class of job.